Retrobulbar primitive neuroectodermal tumor in a squirrel monkey (Saimiri sciureus).

Abstract

BACKGROUND: A 2.8-year-old female captive-bred common squirrel monkey (Saimiri sciureus) showed exophthalmos of the right eye, and the eye was surgically enucleated. A tumor mass was found in the eye. METHODS: Formalin-fixed tumor samples were examined histopathologically and immunohistochemically for diagnosis. RESULTS: The retrobulbar tumor mass adhered to the sclera and infiltrated the choroid. Histopathologically, tumor cells were pleomorphic, arranged in a sheet pattern, and mimicked primitive neuroectodermal cells. The tumor cells were strongly positive for precursor neuronal cell markers (beta III tubulin, neuron-specific enolase, vimentin, nestin, doublecortin, oligo2, and S-100), but negative for mature cell markers (cytokeratin, neurofilament, and glial fibrillary acidic protein) and a retinoblastoma marker (rhodopsin). CONCLUSIONS: This is the first reported case for the retrobulbar location of primitive neuroectodermal tumor in non-human primates.